LED package and backlight assembly for LCD comprising the same

ABSTRACT

An LED package used as a light source in a backlight assembly for an LCD includes a substrate, a plurality of light scattering protrusions on the upper surface of the substrate, LEDs separated from each other by designated intervals and arranged in a line on the substrate, and a molding portion, for sealing the upper surface of the substrate including the LEDs, and having an upper surface including two cylindrical surface sections. Each of the cylindrical surface sections has a curvature for totally reflecting light emitted from the LEDs.

The present application is based on, and claims priority from, KoreanApplication Number 2004-38107, filed May 28, 2004, the disclosure ofwhich is hereby incorporated by reference herein in the entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an LED (Light Emitting Diode) packageused as a light source for a backlight assembly for an LCD, and abacklight assembly for an LCD comprising the same. More particularly,the present invention relates to an LED package having improveduniformity in luminance and color of light so as to be used as a lightsource for a backlight assembly, and a backlight assembly for an LCDcomprising the same.

2. Description of the Related Art

Generally, LCDs (Liquid Crystal Displays) are passive optical elements,which cannot emit light by itself, and thus displaying images using abacklight assembly attached to a rear surface of an LCD panel. Recentbacklight assemblies having various structures have been developed tosatisfy slim and lightweight trends for assuring competitiveness ofobtained products. Particularly, the LCDs are mainly used in notebookcomputers and wall-mounted large TVs, thus being required to satisfy theslim and lightweight trends.

A cold cathode fluorescent lamp (hereinafter, referred to as a “CCFL”)was used as a conventional light source for generating light for theabove backlight assemblies, but is now being replaced with an LED havinga high luminance so as to meet the slim and lightweight trends. Whilethe conventional CCFL is a line light source for emitting a nearlyuniform white ray to a designated length, the LED is a point lightsource for emitting a single colored ray. Accordingly, a great deal ofresearch into emitting a white ray having uniform luminance to adesignated length or designated dimensions is currently underway.

FIG. 1 is a schematic view of a conventional backlight source for an LCDusing an LED. With reference to FIG. 1, the conventional backlightsource 10 comprises LED packages 11, which are spaced from each other bydesignated intervals, and a light guide plate 12 provided with adesignated pattern 121 formed thereon and separated from the LEDpackages 11 by a designated distance (d).

Each of the LED packages 11 of the above conventional backlight source10 may be one package including RGB (Red, Green and Blue) LEDs, or isone of the above colored LEDs. In order to obtain light having uniformluminance, it is most preferable that a plurality of LED packages bedensely arranged. However, the dense arrangement of the LED packagesincreases costs of the light source and the electric power consumptionrate, thus being incapable of being practically employed.

Accordingly, as shown in FIG. 1, the LED packages 11 are spaced fromeach other by designated intervals. In this case, dark regions (D) aregenerated due to emitting angle of light emitted from the LED packages11. In order to reduce the effect of the dark regions (D), the lightguide plate 12 must be separated from the LED packages 11 by asufficient distance (d). The distance (d) between the light guide plate12 and the LED packages 11 increases the volume of the LCD, thus havinga negative effect on the slim and lightweight trends.

The light guide plate 12 is necessary to obtain a uniform white ray bymixing red, green and blue rays generated from the LED packages 11. Thelight guide plate 12 is provided with the designated pattern 121 formedthereon, thereby extending an optical route in the restricted area andfacilitating the mixing of the colored rays.

However, the light guide plate 12, separated from the LED packages 11 bythe designated distance (d), increases the size of the LCD, and theintensity of light emitted from the LED packages 11 is concentrated onthe central area, thus having a negative effect on the miniaturizationof the LCD and deteriorating the uniformity of luminance.

Accordingly, there are required a novel LED package, which is usable asa light source for a backlight assembly of an LCD using an LED, and alight source, using the same, which provides a white ray having uniformluminance to a designated length and designated dimensions.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above problems, andit is an object of the present invention to provide an LED package, usedas a light source for a backlight assembly of an LCD, which provides asufficient optical route so that rays generated from one LED or more aresufficiently mixed to produce a white ray having uniform color andluminance.

It is another object of the present invention to provide a backlightassembly for an LCD comprising the above LED packages.

In accordance with one aspect of the present invention, the above andother objects can be accomplished by the provision of an LED packagecomprising: a substrate; one LED or more separated from each other bydesignated intervals and arranged in a line on the substrate; and amolding portion, for sealing the upper surface of the substrateincluding the LEDs, provided with an upper surface including twocylindrical surface sections, wherein each of the cylindrical surfacesections has a curvature for totally reflecting light emitted from theLEDs.

Preferably, the LEDs may be at least a pair of LEDs for respectivelyemitting complementary colored rays.

Preferably, the LEDs may be arranged in a line just below anintersection line where the two cylindrical surface sections meet.

Preferably, the molding portion may be made of a transparent epoxyhaving a refractivity higher than that of air.

Preferably, the upper surface of the substrate may be coated with amaterial, which does not absorb light, and a plurality of lightscattering means may be protruded from the upper surface of thesubstrate. More preferably, the light scattering means may have dot orstrip shapes, and the light scattering means may be aligned such thatthe intervals between the light scattering means distant from the lightsource are narrower than the intervals between the light scatteringmeans close to the light source.

In accordance with a further aspect of the present invention, there isprovided a backlight assembly for an LCD, attached to a rear surface ofan LCD panel, the backlight assembly comprising: a light sourcemanufactured by connecting a plurality of the above LED packages in adirection perpendicular to the arrangement line of one LED or more; alight guide plate, installed at one side of the light source, forcausing light generated from the light source to be uniformly incidenton the LCD panel; a diffusion sheet, provided on one surface of thelight guide plate toward the LCD panel, for uniformly diffusing thelight incident from the light guide plate; and at least one convergencesheet, provided on one surface of the diffusion sheet toward the LCDpanel, for converging the light diffused by the diffusion sheet in adirection perpendicular to the plane of the LCD panel.

In case that the length and the width of the light source are nearly thesame, the light source is used as a surface light source for irradiatinglight directly onto the rear surface of the LCD panel. In this case, thebacklight assembly comprises: a light source manufactured by connectinga plurality of the above LED packages in a direction perpendicular tothe arrangement line of one LED or more; a diffusion sheet, provided onone surface of the light source toward the LCD panel, for uniformlydiffusing the light incident from the light source; and at least oneconvergence sheet, provided on one surface of the diffusion sheet towardthe LCD panel, for converging the light diffused by the diffusion sheetin a direction perpendicular to the plane of the LCD panel.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a schematic view of a conventional backlight source for an LCDusing an LED;

FIG. 2 a is a perspective view of an LED package in accordance with oneembodiment of the present invention;

FIG. 2 b is a top view of the LED package shown in FIG. 2 a;

FIG. 2 c is a front view of the LED package shown in FIG. 2 a;

FIG. 3 a is a perspective view of a light source comprising the LEDpackage shown in FIG. 2 a;

FIG. 3 b is a top view of the light source comprising the LD packageshown in FIG. 2 a;

FIGS. 4 a and 4 b are schematic views illustrating an optical route ofthe light source comprising the LED package shown in FIG. 2 a;

FIG. 5 a is a perspective view of an LED package in accordance withanother embodiment of the present invention;

FIG. 5 b is a top view of the LED package shown in FIG. 5 a;

FIG. 5 c is a front view of the LED package shown in FIG. 5 a;

FIG. 6 is a perspective view of a light source comprising the LEDpackage shown in FIG. 5 a;

FIG. 7 is an exploded perspective view of a backlight assembly for anLCD comprising the light source shown in FIG. 3 a; and

FIG. 8 is an exploded perspective view of a backlight assembly for anLCD comprising the light source shown in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, preferred embodiments of the present invention will be described indetail with reference to the annexed drawings.

FIG. 2 a is a perspective view of an LED package in accordance with afirst embodiment of the present invention. FIG. 2 b is a top view of theLED package in accordance with the first embodiment of the presentinvention. FIG. 2 c is a front view of the LED package in accordancewith the first embodiment of the present invention. With reference toFIGS. 2 a to 2 c, the LED package 20 in accordance with the firstembodiment of the present invention comprises a substrate 21, LEDs (R,G, and B) separated from each other by designated intervals and arrangedin a line on the substrate 21, and a molding portion 22, for sealing theupper surface of the substrate 21 including the LEDs (R, G, and B),provided with an upper surface including two cylindrical surfacesections.

Although the LED package 20 in accordance with this embodiment of thepresent invention employs LEDs, respectively emitting three coloredrays, i.e., red, green and blue rays, other type LEDs may be employed byLED packages. For example, since complementary colored rays are mixed toproduce a white ray, at least one pair of LEDs for respectively emittingcomplementary colored rays may be employed by the LED package.Otherwise, at least one LED for emitting a white ray using luminescentmaterial may be employed by the LED package. It would be appreciated bythose skilled in the art that the number of the LEDs and colors of lightemitted by the LEDs are not limited.

The substrate 21 may be a general insulating substrate made of ceramic,etc. The upper surface of the substrate 21 is coated with a material,which does not absorb light, and light scattering means 211 areprotruded from the upper surface of the substrate 21.

Although the light scattering means 211 shown in FIGS. 2 a to 2 c areformed to have dot shapes, the light scattering means 211 may be formedto have strip shapes in parallel with the arrangement line of the LEDs(R, G, and B). Preferably, the light scattering means 211 are alignedsuch that the intervals between the light scattering means 211 distantfrom the LEDs (R, G, and B) are narrower than the intervals between thelight scattering means 211 close to the LEDs (R, G, and B). Theuniformity of the light emitted from the LEDs (R, G, and B) is properlyadjusted by the shape and arrangement of the light scattering means 211.

The LEDs (R, G, and B) include a red LED (R), a green LED (G) and a blueLED (B), and are preferably separated from each other by designatedintervals and arranged in a line.

The molding portion 22 seals the upper surface of the substrate 21including the LEDs (R, G, and B), and the upper surface of the moldingportion 22 has two cylindrical surface sections. The two cylindricalsurface sections serve to totally reflect light emitted from the LEDs(R, G, and B) without refraction. The two cylindrical surface sectionsmeet at an intersection line 22 a, and, as shown in FIG. 2 b, the LEDs(R, G, and B) are arranged in a line just below the intersection line 22a. The above arrangement of the LEDs (R, G, and B) is more apparentlyillustrated in FIG. 2 c.

The molding portion 22 is made of a transparent epoxy having arefractivity higher than that of air. In case that light is incidentfrom a medium having an optically high density (i.e., a material havinga high refractivity) on a medium having an optically low density (i.e.,a material having a low refractivity), when an incident angle is morethan a designated angle (critical angle), the light is totally reflectedby an interface therebetween, thereby being incapable of producingrefracted light. This is referred to as “total reflection”, and theminimum value of the incident angle for achieving the total reflectionis referred to as “critical angle”. In order to totally reflect thelight emitted from the LEDs (R, G, and B) at the upper surface of themolding portion 22, the refractivity of the molding portion 22 must behigher than that of air outside the molding portion 22.

Each of the cylindrical surface sections of the molding portion 22 has acurvature for totally reflecting the light emitted from the LEDs (R, G,and B). That is, the curvatures of the cylindrical surface sections ofthe molding portion 22 are determined such that the incident angle ofthe light emitted from the LEDs (R, G, and B) on the upper surface ofthe molding portion 22 is higher than the critical angle, therebyallowing the light emitted from the LEDs (R, G, and B) not to be emittedto the outside of the molding portion 22 and to be reflected again intothe inside of the molding portion 22. Thus, the total reflectionlengthens the optical traveling route, and allows colored rays to beuniformly mixed. Further, the light emitted from the LEDs (R, G, and B)is not concentrated into a central area and is uniformly directed towardthe overall upper surface of the molding portion 22.

A line light source used in a backlight assembly for an LCD havingdesignated width and length is manufactured by connecting a plurality ofthe LED packages 20 in accordance with the above embodiment of thepresent invention in a direction perpendicular to the arrangement lineof the LEDs (R, G, and B). In this case, the LED packages 20 are used ascells constituting the line light source.

As shown in FIGS. 3 a and 3 b, a light source obtained by connecting aplurality of the LED packages 20, serving as cells, in accordance withthe above embodiment comprises a substrate 31, a plurality of LED arrays(A) separated from each other by designated intervals, each LED arrayincluding red, green and blue LEDs (R, G and B), and a molding portion32, for sealing the upper surface of the substrate 31 including the LEDarrays (A), provided with an upper surface including a plurality ofcylindrical surface sections disposed perpendicularly to the arrangementline of the LEDs (R, G, and B).

In order to use the above-described light source as a line light source,the length of the light source in the direction of the arrangement lineof the LEDs (R, G, and B), i.e., the transverse direction, iscomparatively short, and the length of the light source in the directionperpendicular to the arrangement line of the LEDs (R, G, and B), i.e.,the longitudinal direction, is comparatively long. The above line lightsource is used as a light source of a backlight assembly for an LCDusing a side light source.

The light source comprising the LED packages is not limited to the linelight source. In case that the transverse and longitudinal lengths ofthe light source are approximately the same, the light source may beused as a surface light source. The surface light source employing theLED packages in accordance with this embodiment may be used as a lightsource of a backlight assembly for an LCD, which directly irradiateslight to an LCD panel.

An example of the light source comprising the LED packages in accordancewith this embodiment, which is used as a light source of a backlightassembly for an LCD, will be described in detail later.

As described above, the light generated from the LEDs (R, G, and B) istotally reflected by the interface between external air and the moldingportion 32 made of epoxy and provided with the upper surface including aplurality of the cylindrical surface sections, and is directed again tothe inside of the molding portion 32. The reflected light is reflectedagain by light scattering means 311 disposed on the upper surface of thesubstrate 31 so that a part of the light is emitted to the outside ofthe molding portion 32 and the other part of the light is reflected tothe inside of the molding portion 32. That is, the light generated fromthe LEDs (R, G, and B) has an extended optical route in the moldingportion 32 in the longitudinal direction, thereby allowing colors ofrays to be uniformly mixed, and preventing the light from beingconcentrated on the upper surfaces of the LEDs (R, G, and B) so thatlight having uniform luminance is emitted to the overall upper surfaceof the molding portion 32.

Now, with reference to FIGS. 4 a and 4 b, a function of theabove-described light source of the present invention will be describedin detail.

With reference to FIG. 4 a, light (L1) emitted from an LED1 does notpass through the upper surface of a molding portion 42, and is totallyreflected by the molding portion 42. Since the incident angle of thelight (L1) onto a point of one of the cylindrical surface sections ofthe molding portion 42 is larger than a critical angle, the light (L1)is totally reflected by the cylindrical surface section of the moldingportion 42. Accordingly, the cylindrical surface section of the moldingportion 42 must have a curvature capable of totally reflecting lightemitted from the LEDs. The light (L1) emitted from the LED1 is firsttotally reflected by the upper surface of the molding portion 42, issecondarily totally reflected by the upper surface of the moldingportion 42, collides with light scattering means 411, and is thenemitted upwardly. In the same manner, light (L2) emitted from an LED2 istotally reflected three times by the upper surface of the moldingportion 42, collides with the light scattering means 411 formed on thesubstrate 41, and is then emitted upwardly.

As described above, the light emitted from the LEDs is not directlyemitted upwardly, but is reflected several times by the molding portion42, thereby having an extended optical traveling route. In case thatLEDs, respectively emitting three colored rays, i.e., red, green andblue rays, are used, the extended optical traveling route facilitatesthe mixing of the red, green and blue rays, and disperses the light,thereby eliminating the generation of dark regions and allowing lighthaving uniform luminance to be emitted from the overall area of the linelight source. Since the above line light source emits the white rayhaving the uniform luminance, the line light source is used as a lightsource of a backlight assembly for an LCD.

FIG. 4 b is a schematic view illustrating in detail the total reflectionof light by the molding portion 42. As shown in FIG. 4 b, light (L3)emitted from an LED3 is incident onto a point (P) of the molding portion42. Here, in case that the incident angle (θ) between the normal line ofthe slope of the cylindrical surface section at the point (P) and theincident light (L3) is larger than the critical angle, the light (L3) istotally reflected by the cylindrical surface section of the moldingportion 42. Accordingly, the curvature of cylindrical surface section ofthe molding portion 42 is suitably determined in consideration of therefractivity of a transparent epoxy used as a material of the moldingportion 42 and the critical angle thereof.

FIG. 5 a is a perspective view of an LED package in accordance with asecond embodiment of the present invention. FIG. 5 b is a top view ofthe LED package in accordance with the second embodiment of the presentinvention. FIG. 5 c is a front view of the LED package in accordancewith the second embodiment of the present invention. With reference toFIGS. 5 a to 5 c, the LED package 50 in accordance with the secondembodiment of the present invention comprises a substrate 51, an LEDgroup (RGB) including red, green and blue LEDs and placed at a point onthe substrate 51, and a molding portion 52, for sealing the uppersurface of the substrate 51 including the LED group (RGB), provided withan upper surface including four curved surfaces meeting at oneintersection point 52 a. The LED package 50 in accordance with thisembodiment further comprises a cup 53 placed on the upper surface of thesubstrate 51 for receiving the LED group (RGB).

Although the LED package 50 in accordance with this embodiment of thepresent invention employs the LED group including three LEDsrespectively emitting three colored rays, i.e., red, green and bluerays, other type LEDs may be employed by LED packages to generate awhite ray. For example, since complementary colored rays are mixed toproduce a white ray, at least one pair of LEDs for respectively emittingcomplementary colored rays may be employed by the LED package.Otherwise, at least one LED for emitting a white ray using luminescentmaterial may be employed by the LED package. It would be appreciated bythose skilled in the art that the number of the LEDs and colors of lightemitted from the LEDs are not limited.

In this embodiment, the substrate 51 may be a general insulatingsubstrate made of ceramic, etc. The upper surface of the substrate 51 iscoated with a material, which does not absorb light, and lightscattering means 511 are protruded from the upper surface of thesubstrate 51.

Although the light scattering means 511 shown in FIGS. 5 a to 5 c areformed to have dot shapes, the light scattering means 511 may be formedto have concentrically circular shapes centering on the LED group (RGB)or the cup 53. Preferably, the light scattering means 511 are alignedsuch that the intervals between the light scattering means 511 distantfrom the LED group (RGB) or the cup 53 are narrower than the intervalsbetween the light scattering means 511 close to the LED group (RGB) orthe cup 53. The uniformity of the light emitted from the LEDs of the LEDgroup (RGB) is properly adjusted by the shape and arrangement of thelight scattering means 511.

The LED group (RGB) includes a red LED, a green LED and a blue LED so asto generate a white ray, and is placed on the cup 53. Preferably, theinner surface of the cup 53 is coated with a material having a highreflectivity so that light emitted from side or lower surface of theLEDs is partially reflected by the inner surface of the cup 53.

The molding portion 52 seals the upper surface of the substrate 51including the LED group (RGB) or the cup 53, and the upper surface ofthe molding portion 52 includes four curved surfaces meeting at theintersection point 52 a. The four curved surfaces serve to totallyreflect light emitted from the LED group (RGB) without refraction. Thefour curved surfaces meet at the intersection point 52 a, and, as shownin FIG. 5 b, the LED group (RGB) is arranged just below the intersectionpoint 52 a. The above arrangement of the LED group (RGB) is more clearlyillustrated in FIG. 5 c.

The molding portion 52 is made of a transparent epoxy having arefractivity higher than that of air. In order to totally reflect thelight emitted from the LED group (RGB) at the upper surface of themolding portion 52, the refractivity of the molding portion 52 must behigher than that of air outside the molding portion 52.

Each of the curved surfaces of the molding portion 52 has a curvaturecapable of totally reflecting the light emitted from the LED group(RGB). That is, the curvatures of the curved surfaces of the moldingportion 52 are determined such that the incident angle of the lightemitted from the LED group (RGB) onto the upper surface of the moldingportion 52 is higher than the critical angle, thereby allowing the lightemitted from the LED group (RGB) not to be emitted to the outside and tobe reflected again to the inside of the molding portion 52. Thus, thetotal reflection lengthens the optical traveling route, and allowsvarious colored rays to be uniformly mixed. Further, the light emittedfrom the LED group (RGB) is not concentrated on the upper surface of theLED group (RGB) and is uniformly directed toward the overall uppersurface of the molding portion 52.

A light source used in a backlight assembly for an LCD is manufacturedby connecting a plurality of the LED packages 50 in longitudinal andtransverse directions in accordance with the above embodiment of thepresent invention. In case that a bar-shaped light source ismanufactured by connecting the LED packages 50 in accordance with thisembodiment, the manufactured light source is used as a line light sourceused by a backlight unit for an LCD, which is a side light source. Incase that a plate-shaped light source is manufactured by connecting theLED packages 50 in accordance with this embodiment, the manufacturedlight source is used as a surface light source, which directlyirradiates light to a rear surface of an LCD panel. In these cases, theLED packages 50 are used as cells constituting the light source.

As shown in FIG. 6, a light source obtained by connecting a plurality ofthe LED packages 50, serving as cells, in longitudinal and transversedirections in accordance with the above embodiment comprises a substrate61, a plurality of LED groups, each LED group including red, green andblue LEDs disposed on the upper surface of the substrate 61 inlongitudinal and transverse directions so that the red, green and blueLEDs are separated from each other by designated intervals, a moldingportion 62, for sealing the upper surface of the substrate 61 includingthe LED groups, provided with an upper surface including a plurality ofcurved surfaces disposed in longitudinal and transverse directions, anda cup 63 placed on the upper surface of the substrate 61 for receivingthe LED groups.

The above-described light source, in the same manner as the principleand function as illustrated with reference to FIGS. 4 a and 4 b, has anextended optical route in the molding portion, thereby allowing the red,green and blue rays to be mixed into a white ray having uniformluminance. However, while the optical route of the light sourcecomprising the LED packages in accordance with the first embodiment asshown in FIGS. 4 a and 4 b is extended to a direction perpendicular tothe arrangement line of the LEDs, the optical route of the light sourcecomprising the LED packages in accordance with the second embodiment isextended to all directions. Accordingly, it is preferable that the LEDpackage in accordance with the first embodiment of the present inventionas shown in FIG. 2 a is applied to a line light source, and the LEDpackage in accordance with the second embodiment of the presentinvention is applied to a surface light source.

Now, with reference to FIGS. 7 and 8, examples of light sourcescomprising LED packages in accordance with the above two embodiments ofthe present invention will be described in detail.

FIG. 7 is an exploded perspective view of a side light source-typebacklight assembly for an LCD. With reference to FIG. 7, the backlightassembly comprises a light source 71 manufactured by connecting aplurality of LED packages in accordance with one embodiment of thepresent invention in longitudinal and/or transverse directions, a lightguide plate 72, installed at one side of the light source 71, forcausing light generated from the light source 71 to be uniformlyincident on an LCD panel 77, a diffusion sheet 74, provided on onesurface of the light guide plate 72 toward the LCD panel 77, foruniformly diffusing the light incident from the light guide plate 72,and at least one convergence sheet 75, provided on one surface of thediffusion sheet 74 toward the LCD panel 77, for converging the lightdiffused by the diffusion sheet 74 in a direction perpendicular to theplane of the LCD panel 77.

Although the light source 71 shown in FIG. 7 is a bar-shaped line lightsource obtained by connecting the LED packages in accordance with thefirst embodiment of the present invention in a direction perpendicularto the arrangement line of the LEDs, it would be appreciated by thoseskilled in the art that a bar-shaped line light source obtained byconnecting the LED packages in accordance with the second embodiment ofthe present invention is used as the light source 71.

A backlight assembly using a conventional cold-cathode lamp requiresreflecting means surrounding the cold-cathode lamp for reflecting light,emitted to a side opposite to the light guide plate, toward the lightguide plate. However, since the upper surface of the substrate of thelight source of the present invention is coated with a reflectivematerial, the light source of the present invention emits light having asufficient density toward the light guide plate without using anyreflecting means, thus not requiring the reflecting means. Accordingly,the light source using the LED packages of the present invention isadvantageous in terms of lightweight and slim trends of the LCD.

Further, the above-described light source using the LED packages of thepresent invention assures a sufficient optical route therein, thushaving uniformity in color and optical intensity of light approximatelythe same as those of the conventional cold-cathode lamp.

The light guide plate 72 is made of a transparent plastic material, suchas acryl, such that the light guide plate 72 has an inclined lowersurface and a level upper surface (or an inclined upper surface and alevel lower surface). The light generated from the light source 71passes through the upper surface of the light guide plate 72, and isdirected toward the LCD panel 77 above the light guide plate 72.Accordingly, various patterns, such as a finely dotted pattern, forchanging the traveling direction of the light generated from the lightsource 71 are printed on the lower surface of the light guide plate 72.

A reflection plate 73 is placed on the lower surface of the light guideplate 72. The reflection plate 73 reflects a part of the light travelingtoward the lower surface of the light guide plate 72, which is notreflected by the finely dotted pattern, to the upper surface of thelight guide plate 72, thereby reducing loss of the light incident on theLCD panel 77 and improving uniformity of the light transmitted towardthe upper surface of the light panel 72. As described above, the lightguide plate 72 and the reflection plate 73 guide the light generatedfrom the light source 71 toward the upper surface of the light guideplate 72.

The light having passed through the upper surface of the light guideplate 72 includes rays inclined against the upper surface of the lightguide plate 72 at various angles as well as rays perpendicular to theupper surface of the light guide plate 72. The diffusion sheet 74 placedon the upper surface of the light guide plate 72 serves to diffuse thelight incident from the light guide plate 72, thereby preventing thelight from being partially concentrated. The convergence sheet 75includes a first convergence sheet 75 a and a second convergence sheet75 b. Further, the diffusion sheet 74 serves to reduce the incidentangle of the light traveling on the first convergence sheet 75 a.

Each of the first convergence sheet 75 a and the second convergencesheet 75 b includes a plurality of triangular prisms uniformly arrangedon an upper surface thereof. The arrangement of the prisms of the firstconvergence sheet 75 a and the arrangement of the prisms of the secondconvergence sheet 75 b cross each other at a designated angle. The firstand second convergence sheets 75 a and 75 b serve to converge the light,which has been diffused by the diffusion sheet 74, into the LCD panel 77in a direction perpendicular to the plane of the LCD panel 77, therebyallowing the light having passed through the first and secondconvergence sheets 75 a and 75 b to be vertically incident on aprotective sheet 76. Thus, since the light having passed through thefirst and second convergence sheets 75 a and 75 b travels nearlyvertically, the distribution of luminance on the protective sheet 76 isuniform. Although the light source of FIG. 7 employs two convergencesheets, the light source may employ a single convergence sheet whenoccasion demands.

The protective sheet 76 placed on the upper surface of the secondconvergence sheet 75 b serves to diffuse the light for making thedistribution of the light uniform, as well as to protect the surface ofthe second convergence sheet 75 b. The LCD panel 77 is placed on theprotective sheet 76.

FIG. 8 is an exploded perspective view of a surface light source-typebacklight assembly for an LCD, which irradiates light directly to a rearsurface of an LCD panel. With reference to FIG. 8, the backlightassembly comprises a light source 81 manufactured by connecting aplurality of LED packages in accordance with one embodiment of thepresent invention in longitudinal and/or transverse directions, adiffusion sheet 84, provided on one surface of the light source 81toward an LCD panel 87, for uniformly diffusing the light incident fromthe light source 81, and at least one convergence sheet 85, provided onone surface of the diffusion sheet 84 toward the LCD panel 87, forconverging the light diffused by the diffusion sheet 84 in a directionperpendicular to the plane of the LCD panel 87.

Although the light source 81 shown in FIG. 8 is a plate-shaped surfacelight source obtained by connecting the LED packages in accordance withthe second embodiment of the present invention in longitudinal andtransverse directions, it would be appreciated by those skilled in theart that a plate-shaped surface light source having nearly the samelongitudinal and transverse lengths obtained by connecting the LEDpackages in accordance with the first embodiment of the presentinvention is used as the light source 81.

As shown in FIG. 8, a surface light source, for irradiating lightdirectly onto the rear surface of the LCD panel 87, must emit light ofuniform luminance and color throughout the overall surface thereof. Thelight source comprising the LED packages of the present inventionassures a sufficient optical route in the packages, thus uniformlymixing colors of rays and reducing the concentration of opticalintensity of light. Accordingly, the light source comprising the LEDpackages of the present invention serves as a surface light source forirradiating light directly onto the rear surface of the LCD panel.Particularly, the LED package in accordance with the second embodimentof the present invention has an extended optical route of light emittedfrom the LEDs in all directions. Thus, preferably, a plate-shapedsurface light source comprises a plurality of the LED packages inaccordance with the second embodiment of the present invention, whichare connected in longitudinal and transverse directions.

Particularly, in the example as shown in FIG. 8, since the light source81 irradiates light onto the overall rear surface of the LCD panel 87and the sufficient optical route in the light source 81 is assured, thebacklight assembly obtains uniformity in color and intensity of light,thus not requiring a light guide plate and a reflection plate placed onthe lower surface of the light guide plate. Accordingly, the lightsource comprising the LED packages of the present invention sufficientlysatisfies the lightweight and slim trends of the LCD.

The diffusion sheet 84, first and second convergence sheets 85 a and 85b, and a protective sheet 86 are sequentially stacked on the uppersurface of the light source 81. Here, functions and operations of thediffusion sheet 84, the first and second convergence sheets 85 a and 85b and the protective sheet 86 are the same as those of the diffusionsheet 74, the first and second convergence sheets 75 a and 75 b and theprotective sheet 76 shown in FIG. 7.

As described above, the LED package in accordance with the presentinvention is used as a cell constituting a bar-shaped line light sourceand a plate-shaped surface light source, and assures a sufficientoptical traveling route therein, thereby achieving uniformity in colorand intensity of light. Further, since the LED package is used as thecell, the number of the LED packages is adjusted based on the shape andsize of the LCD. Thereby, it is possible to manufacture a light sourceby a simple process and to easily change the design of the light sourceif necessary.

As apparent from the above description, the present invention providesan LED package, which assures a sufficient optical traveling routetherein, thereby generating a white ray having improved uniformity inluminance and color.

Further, the present invention provides a light source obtained byconnecting a plurality of the LED packages serving as cells. Thereby, itis possible to produce a light source of a backlight assembly for an LCDwithout using a plurality of LEDs. Further, the light source is simplyproduced by adjusting the number of the LED packages based on the shapeand size of the LCD, and the design of the light source is easilychanged if necessary.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. An LED package, comprising: a substrate; a plurality of lightscattering means protruding from the upper surface of the substrate;LEDs separated from each other by designated intervals and arranged in aline on the substrate; and a molding portion sealing the upper surfaceof the substrate including the LEDs, said molding portion having anupper surface including two cylindrical surface sections; wherein eachof the cylindrical surface sections has a curvature configured fortotally reflecting light emitted from the LEDs.
 2. The LED package asset forth in claim 1, wherein the LEDs are at least a pair of LEDs forrespectively emitting complementary colored rays.
 3. The LED package asset forth in claim 1, wherein the line along which the LEDs are arrangedis located just below an intersection line where the two cylindricalsurface sections meet.
 4. The LED package as set forth in claim 1,wherein the molding portion is made of a transparent epoxy having arefractivity higher than that of air.
 5. The LED package as set forth inclaim 1, wherein the upper surface of the substrate is coated with amaterial, which does not absorb light.
 6. The LED package as set forthin claim 1, wherein the light scattering means have dot or strip shapes.7. The LED package as set forth in claim 1, wherein the light scatteringmeans are aligned such that the intervals between the light scatteringmeans distant from the line of the LEDs are narrower than the intervalsbetween the light scattering means close to the line of the LEDs.
 8. TheLED package as set forth in claim 1, wherein the LEDs include at least ared light emitting LED, at least a green light emitting LED, and atleast a blue light emitting LED.
 9. A light source comprising aplurality of connected LED packages, each as being set forth in claim 1.10. A backlight assembly adapted to be attached to a rear surface of anLCD panel, said backlight assembly comprising: a light source comprisinga plurality of connected LED packages, each as being set forth in claim1; a light guide plate, installed at one side of the light source, forguiding light generated from the light source toward the LCD panel; adiffusion sheet, provided on one surface of the light guide plate thatis adapted to face toward the LCD panel, for uniformly diffusing thelight incident from the light guide plate; and at least one convergencesheet, provided on one surface of the diffusion sheet that is adapted toface toward the LCD panel, for converging the light diffused by thediffusion sheet in a direction perpendicular to the plane of the LCDpanel.
 11. A backlight assembly adapted to be attached to a rear surfaceof an LCD panel, said backlight assembly comprising: a light sourcecomprising a plurality of connected LED packages, each as being setforth in claim 1; a diffusion sheet, provided on one surface of thelight source that is adapted to face toward the LCD panel, for uniformlydiffusing the light incident from the light source; and at least oneconvergence sheet, provided on one surface of the diffusion sheet thatis adapted to face toward the LCD panel, for converging the lightdiffused by the diffusion sheet in a direction perpendicular to theplane of the LCD panel.
 12. An LED package, comprising: a substrate; aplurality of light scattering protrusions on the upper surface of thesubstrate; LEDs separated from each other by designated intervals andarranged in a line on the substrate; and a molding portion sealing theupper surface of the substrate including the LEDs, said molding portionhaving an upper surface including two cylindrical surface sections;wherein each of the cylindrical surface sections has a curvatureconfigured for totally reflecting light emitted from the LEDs.
 13. TheLED package as set forth in claim 12, wherein the LEDs are at least apair of LEDs for respectively emitting complementary colored rays. 14.The LED package as set forth in claim 12, wherein the line along whichthe LEDs are arranged is located just below an intersection line wherethe two cylindrical surface sections meet.
 15. The LED package as setforth in claim 12, wherein the molding portion is made of a transparentepoxy having a refractivity higher than that of air.
 16. The LED packageas set forth in claim 12, wherein the upper surface of the substrate iscoated with a material, which does not absorb light.
 17. The LED packageas set forth in claim 12, wherein the light scattering protrusionscomprise dots or strips.
 18. The LED package as set forth in claim 12,wherein the light scattering protrusions are aligned such that theintervals between the light scattering protrusions farther from the lineof the LEDs are narrower than the intervals between the light scatteringprotrusions closer to the line of the LEDs.
 19. A backlight assemblyadapted to be attached to a rear surface of an LCD panel, said backlightassembly comprising: a light source comprising a plurality of LEDpackages, each as being set forth in claim 12; a light guide plate,installed at one side of the light source, for guiding light generatedfrom the light source toward the LCD panel; a diffusion sheet, providedon one surface of the light guide plate that is adapted to face towardthe LCD panel, for uniformly diffusing the light incident from the lightguide plate; and at least one convergence sheet, provided on one surfaceof the diffusion sheet that is adapted to face toward the LCD panel, forconverging the light diffused by the diffusion sheet in a directionperpendicular to the plane of the LCD panel.
 20. A backlight assemblyadapted to be attached to a rear surface of an LCD panel, said backlightassembly comprising: a light source comprising a plurality of LEDpackages, each as being set forth in claim 12, a diffusion sheet,provided on one surface of the light source that is adapted to facetoward the LCD panel, for uniformly diffusing the light incident fromthe light source; and at least one convergence sheet, provided on onesurface of the diffusion sheet that is adapted to face toward the LCDpanel, for converging the light diffused by the diffusion sheet in adirection perpendicular to the plane of the LCD panel.